[GRASS-dev] vlib api: is area an isle?

[Martin Landa]

Hi,

I am trying to find a way how to determine if an area forms an isle
using vlib API? Eg.

$ v.buffer in=roadsmajor out=rb dist=1000

produces

17 areas (1 area with category + 16 areas (without categories) forms isles)
17 isles (one "universal isle" + 16 "holes" in area)

Is there any way how to determine from topology that given area forms
an isle. Such area has no category, but it's a weak precondition. We
can have areas with no category (no centroid defined for such area)
which do not form isles ("hole in polygon" from simple feature
terminology).

I would like to go through all areas and skip the areas which form isles.

for (area = 1; area <= nareas; area) {
     if (Vect_is_area_isle(Map, area)
        continue;
}

Thanks for any pointers (I just cannot find it), Martin

-- 
Martin Landa <landa.martin gmail.com> * http://geo.fsv.cvut.cz/~landa